ORIGINAL PAPER Using one-dimensional (1D) and two-dimensional (2D) quantitative proton ( 1 H) nuclear magnetic resonance spectroscopy (q NMR) for the identification and quantification of taste compounds in raw onion (Allium cepa L.) bulbs and in aqueous solutions where onion tissues are soaked Audrey Tardieu & Walter De Man & Hervé This Received: 30 June 2010 / Revised: 21 September 2010 / Accepted: 25 September 2010 / Published online: 23 October 2010 # Springer-Verlag 2010 Abstract Solutions obtained by soaking onion (Allium cepa L.) bulbs samples in water are frequently consumed, either directly or as part of dishes, both at home or in the food industry. However, little information is available regarding the extracted metabolites and the extraction mechanisms. In this article, the composition of raw onion extracts and of aqueous solutions where raw onion tissues were soaked was investigated directly by quantitative proton nuclear magnetic resonance spectroscopy (q 1 H NMR). The assignment of NMR signals was performed, with less than 3% (in area) of unidentified peaks. Analyses of one-dimensional 1 H NMR spectra with additional two- dimensional NMR studies showed 20 regions of interest where 3 saccharides, 17 amino acids, and 5 organic acids were detected and quantified. Resonance assignment with chemical shift was done for each saccharide, as well as for each amino acid and organic acid, with additional work on spin–spin coupling pattern and on observed and not observed correlations from correlation spectroscopy studies. Quantification of saccharides was performed and qualified by works on peak decomposition algorithms. Complemen- tary studies by high-performance liquid chromatography, mass spectroscopy and tandem mass spectroscopy, and thin layer chromatography and preparative layer chromatogra- phy were carried out in order to validate the NMR results on identification. Keywords Taste . Quantitative 1 H NMR . Allium cepa L. . Saccharides . Amino acids . Organic acids Introduction Most human food is based on plant tissues, animal tissues and liquids prepared from them, including aqueous solutions obtained by thermal processing of plant or animal tissues in water (“stocks”, “sauces”…). Of course, food is consumed for energy, but the selection of food products is also based on flavor, i.e., the synthetic sensation including taste as one component [1]. Molecules contribute to taste by linking to taste receptors from cells in taste buds [2] but before reaching taste buds, they have to dissolve in water, as they must first migrate from food to saliva. Onions (Allium cepa L.) being among the most widely distributed Liliaceous plants in the world [3] and one of the main vegetables consumed in Europe [4], their content in taste compounds was investigated by many authors [3, 5– 9]. They are used either directly as vegetable, or as a seasoning for a wide variety of food preparations [10]. In both cases, only the bulbous roots (also called the bulb) are used [11]. A. Tardieu : H. This (*) INRA, Groupe de Gastronomie Moléculaire, UMR 1145, 16 rue Claude Bernard, 75005 Paris, France e-mail: herve.this@paris.inra.fr W. De Man Mars Food Belgium, Industrielaan 7, 2250 Olen, Belgium H. This AgroParisTech, Laboratoire de chimie analytique, 16 rue Claude Bernard, 75005 Paris, France Anal Bioanal Chem (2010) 398:3139–3153 DOI 10.1007/s00216-010-4255-x